User:R. Eric Collins/MBL/Felsenstein

From OpenWetWare
Jump to: navigation, search

Phylogeny & Morphometrics

  • genetic covariance
  • selective covariance
    • the same environmental conditions select changes in two or more traits -- even though they may have no genetic covariance
    • arctic: fur coloration, size, limb length; bergman, allen rules
    • all change at same time because environment has changed
    • not that they necessarily have genetic covariance
  • superpositions can be misleading, multiple superpositions correspond to the same change
  • in 1/0 stochastic model, you are just as likely to 'come back' right after switch as much later
    • 'coming back', biologically, seems less likely after long time e.g. the brownian model
  • running the covariance estimator longer only estimates the noise better
  • covariance? 100 numerical values --> 100 presence/absence --> <100 on a tree
    • lose power to measure covariance at each step
  • with genomes, will be able to get QTL within species, see them change across species
  • resign yourself to uncertainty
  • no "post-modern synthesis"

History Lesson

in 1957 the average university got a computer it was as powerful as a singing birthday card today (really?)

  • first numerical phylogeny, of bees, by Sokal and Michener 1957
    • Michener wanted to make phenetic inference into a phylogeny
  • "the most parsimonious thing evolution could do would be to not change anything"